Stoichiometry of mitochondrial cytochromes P‐450, adrenodoxin and adrenodoxin reductase in adrenal cortex and corpus luteum: Implications for membrane organization and gene regulation

We have estimated the concentrations of cytochromes P‐450_scc and P‐450_11β and the electron‐transfer proteins adrenodoxin reductase and adrenodoxin in the adrenal cortex and corpus luteum using specific antibodies against these enzymes. While in the adrenal cortex the concentrations of these enzymes are relatively constant in different animals and show no significant sex differences, in corpora lutea they vary considerably and can increase at least up to fiftyfold over the levels found in the ovary. The average relative concentrations of adrenodoxin reductase, adrenodoxin and P‐450 are 1:3:8 in the adrenal cortex (which has two cytochromes P‐450, P‐450_scc and P‐450_11β, in equal concentrations) and 1:2.5:3 in the corpus luteum (which has only P‐450_scc). We further present evidence that the levels of cytochrome c oxidase also show a degree of correlation with the levels of the mitochondrial steroidogenic enzymes.